class Dog():

    def __init__(self, name ,age):
        '''  初始化name和age '''
        self.name = name
        self.age = age

    def sit(self):
        ''' 模拟小狗被命令蹲下 '''
        print(self.name.title() + "is now sitting.")

    def roll_over(self):
        ''' 模拟小狗被命令打滚 '''
        print(self.name.title() + "rolled over")

my_dog = Dog('willie', 6)
my_dog.sit()
my_dog.roll_over()

print("My dog's name is " + my_dog.name.title())
print("My dog is " + str(my_dog.age) + "years old.")

your_dog = Dog('lucy', 3)
your_dog.sit()
your_dog.roll_over()
print("Your dog's name is " + your_dog.name.title())
print("Your dog is " + str(your_dog.age) + "years old.")
